Incident Overview
An accident occurred during ground refueling of a Boeing 727 aircraft. The captain was aware that the refueler was using known quantity refueling procedures because the aircraft's fuel gauge was inoperative. The flight engineer was permitted by the captain to activate the B hydraulic system and the ground interconnect switch without first confirming that ground personnel were clear of the leading edge slats.
Sequence of Events
While the refueler was encountering difficulties with the fueling system, he climbed a ladder to open a fuel panel without informing anyone of his actions. At the same time, the B hydraulic system was activated. This caused the leading edge slats to retract, and the refueler's neck was crushed between the wing and the trailing edge of a slat.
Contributing Circumstances
The activation of the hydraulic system and the lack of positive assurance that ground personnel were clear of the slats were key factors in the accident, as the slats retracted while the refueler was in an unsafe position.
Conclusion
The incident highlights the need for clear communication and positive confirmation of personnel safety before activating aircraft systems. The refueler's failure to communicate his actions and the flight crew's failure to ensure the area was clear led to the accident.